There has been a bit of a mystery over the Norwegian climate sensitivity study that found evidence of low climate sensitivity. In particular, a number of commentators have noted that there doesn't appear to be a peer reviewed paper as yet.

It appears from the Twittersphere that the press release was issued by the Norwegian Funding body, based on an internal report on the project from the scientists concerned, and without the approval of the scientists.

While we wait for a paper (and the data and code), there is this magazine article about the study (from page 8). The lead researcher appears to be Ragnhild Bieltvedt Skeie. Here are the key conclusions:

The RF time series...have been used in a Bayesian approach to constrain the climate sensitivity in a recent PhD thesis from the Institute of Geoscience, University of Oslo (Skeie, 2012) in collaboration with the Norwegian Computing Center. The probability density function for the climate sensitivity in this study is tighter and with a lower posterior mean value (1.9°C) compared to previous studies using the instrumental record to estimate the climate sensitivity (Hegerl et al., 2007). Also, values of the climate sensitivity larger than 4.5˚C are excluded. The observed ocean heat content over the recent decade is found to be important for the better constrained climate sensitivity in this study, however the historical ocean heat content data series have large uncertainties. In addition to improved data for the storage of heat in the ocean, improved knowledge of how aerosols affect the clouds and how this effect has altered the energy balance over the last century is crucial in future work for constraining the climate sensitivity.

Reader Comments (8)

I mentioned this the other day to no response, but what is the justification for saying that there is any such thing as a climate sensitivity as an averaged figure applicable globally and for long periods of time and ranges of CO2?

Now, I can see that locally a given change of CO2 has a result, for a small delta. I cannot see how one can assume that that local effect is capable of being averaged and applied globally. Too many things going on. Feedback, tipping points, non-linear whatsits. I am sure that statistical methods as recently discussed, if properly applied, may enable one to quantify that number, but you have to assume the number is there first. What if it isn't?

Adding to the mystery is the fact that they have already published a paper, a year ago, that gives a CS of 1.9. This paper is cited in AR5 ch 10. So why the frenzy over a new paper saying the same result?

Rhoda, Tamsin agrees with you, see the middle of Josh's large panel here.The paper linked above says "The equilibrium climate sensitivity is deﬁned as the temperature increase because of a doubling of the CO2 concentration in the atmosphere when the climate reaches a new steady state", perpetuating the myth that if the climate had a constant 'forcing', it would settle to a steady state.

There was a guy with a thesis from Reading University quoted in the Guardian recently in their search for a lie big enough to beat the reality that it hadn't warmed for 15 years. He said that the climate had very recently changed from warming the air to warming the oceans.

"I couldn't believe my eyes, Mr Attenborough . There were 1 million Wildebeest charging madly toward the city centre. When they hit the suburbs, they slowed down to 30mph and engaged their headlights. They went to a movie then walked home. That was lucky. "

I was kind of expecting to be told how daft I was for writing about my doubts that climate sensitivity is a mere conjecture. No. Nothing at all save a little support from Paul. So I ask, has this one snuck past all examination, or is there a justification somewhere that the climate sensitivity as understood is a useful concept other than as a way to disseminate dodgy predictions as reality-based?

My apologies, I was mislead by a statement in a norwegian blog by the infamous Benestad at the Met-Inst. He pointed to this paper when the Berntsen paper was searched for. This research breakthrough is completely covered-up in nowegian media. Not a single newspaper has reported anything, and Cicero where Berntsen actually works is totally quiet.